Some weeks ago I installed the owncloud client on my Ubuntu system. However, it does not seem to be safe and I want to remove it. I deleted it and apparently it is gone. Unfortunately there is still an persistent entry in the software update. Each time I want to update my system an error aborts everything, because I did not import the public key:
sudo apt-get update ... Reading package lists... Done W: GPG error: http://download.opensuse.org Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 977C43A8BA684223
I just could import the public key and no error message would annoy me any longer. But I don't want to trust this key, but simply remove everything concerning owncloud.
/etc/apt/sources.list, but I cannot find
http://download.opensuse.org. Why? Where does
apt-get get his source list? How can I solve this problem?